JPS5944609B2 - Digital electric shutter that automatically fires strobe light - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital electric shutter that automatically emits strobe light.

Auto strobe itself has already been known for a long time,
It is also customary to attach this to a camera and take a picture when exposure is performed at an inappropriate substitute brightness.

This auto strobe has a limited amount of light emitted depending on the distance at a certain aperture, and provides an appropriate amount of light to the film, and although it is extremely convenient, it also has the following drawbacks. A. When using strobe light,
Each time, you have to manually adjust the shutter time to the X contact, which is cumbersome, and you often forget to adjust it, resulting in failure in taking pictures. B. Although it is an electric shutter, it has an X contact (
(corresponding to a shutter time of 1/60 second) is performed mechanically, which is disadvantageous in terms of construction.

C. This is troublesome because it must be determined each time whether appropriate range photography is possible or whether strobe light should be emitted.

D. The aperture must also be set to a predetermined aperture value each time the flash is fired, which is cumbersome.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital electric shutter that can automatically emit an auto strobe in a low brightness area where camera shake occurs. Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of a digital electric shutter that automatically emits strobe light according to the present invention. In the figure, reference numeral 1 denotes a photoresponse pulse generator that outputs a number of photoresponse pulses corresponding to the intensity of field light as gate outputs of a gate circuit while a gate signal is applied. This photoresponsive pulse generator 1 is
A photoelectric element 2 that receives field light and outputs an electric signal according to the incident light; a photoresponse timer 3 that sets a timer time based on the signal from the photoelectric element 2 and outputs a gate signal of the time width; It includes a first reference pulse generator 4 that generates a reference pulse, and an AND circuit 5 as a gate circuit that controls passing the reference pulse as a photoresponse pulse only during the time that the photoresponse timer 3 is outputting a gate signal. It is configured. Reference numeral 6 denotes a fixed shutter time equivalent pulse generator that outputs a pulse corresponding to a predetermined shutter time (for example, 1/60 second), which includes a second reference pulse generator 7 that generates a reference pulse, and a set A fixed shutter time setting timer 8 which outputs a gate signal "1" with a time width for the timer time and outputs a signal "0" when the time elapses.
and an AND circuit 9 as a gate circuit that allows the reference pulse to pass only while the timer 8 outputs the gate signal "1".

10 is a normally open switch that is closed in conjunction with the shutter release; 11 is a switch that stores a number of photoresponse pulses corresponding to the field light from the photoresponse pulse generator 1, and is referenced by the shutter release; This is a photoresponsive shutter time restoring device which counts reference pulses inputted from a pulse generator 7 via a switch 10 to restore the photoresponsive shutter time and outputs a first shutter closing signal.

This photoresponse shutter time restoration device 11 counts and stores the input photoresponse pulses which are divided into a proper brightness stage and a low brightness stage, and when a signal is stored in the substitute brightness stage, a low brightness signal is detected. a reference pulse counter 13 that counts reference pulses applied via the switch 10; and a first shutter when the count value of this counter 13 matches the stored value of the light response pulse counter 12. The first matching circuit 14 outputs a closing signal.

Each of the counters 12 and 13 has a six-stage configuration from 121 to 126 and from 131 to 136, respectively. In this embodiment, the first stage 121 of the optical response pulse counter 12
The stages from 123 to the third stage are treated as appropriate brightness stages, and the fourth stages 124 to 126 are treated as low brightness stages where camera shake may occur. Reference numeral 15 stores the fixed shutter time equivalent pulse given from the fixed shutter time equivalent pulse generator 6, and counts the reference pulse inputted from the reference pulse generator 7 via the switch 10 upon shutter release to calculate the fixed shutter time ( This is a fixed shutter time restoration device which restores the shutter time (for example, 21/60 seconds) and outputs a second shutter close signal.

This device 15 includes a fixed shutter time equivalent pulse counter 16, a reference pulse counter 13 which also serves as the photoresponsive shutter time restoring device 11, and the counted value of this counter 13 is the stored value of the fixed shutter time equivalent pulse counter 16. a second shutter which outputs a second shutter closing signal when the
It is configured to include a matching circuit 17. counter 16
It also has a 6-stage configuration from 161 to 166. Next, reference numeral 18 denotes an OR circuit as a gate circuit for passing the low luminance signal [1] output from the low luminance stages from the fourth stage 124 to the sixth stage 125 of the photoresponse pulse counter 12;
is an aperture drive circuit that sets the aperture 20 to a predetermined value when the low luminance signal [1] is output from the OR circuit 18.

21 inputs the substitute brightness signal outputted from the OR circuit 18 and the first shutter closing signal outputted from the first coincidence circuit 14, and closes the first shutter when the low brightness signal is absent. A first switching gate circuit 22 that outputs a signal receives the low brightness signal outputted from the OR circuit 18 and the second shutter close signal outputted from the second coincidence circuit 17, and outputs the low brightness signal. A second switching gate circuit 23 outputs the second shutter close signal when the second shutter close signal is present, and when the second shutter close signal is output from the AND circuit 22, it uses this as a trigger signal to cause the auto strobe tube 24 to emit light. 25 is an OR circuit 26 serving as a gate circuit for passing the first or second shutter closing signal from the first and second switching gate circuits 21 and 22;
1 is a shutter closing circuit that closes the shutter when the second shutter closing signal is applied.

This circuit 26 includes a shutter closing electromagnetic magnet 27,
It is configured to include a thyristor 28 and a resistor 29 for controlling the electromagnetic magnet 27. Next, the operation of such an electric shutter will be explained.

First, a case where the field light is in the appropriate luminance range will be described. When the camera is directed toward the subject and the film is wound, a power switch (not shown) is closed in conjunction with the winding of the film, and the light response timer 3 and fixed shutter timer timer 8 are activated to generate gate signals. "1"
emits. These gate signals [1'' are connected to the respective AND circuits 5, 9vC. applied. Therefore, each AND circuit 5
, 9 are opened, so that the photoresponse pulse counter 12
, a light response pulse and a fixed shutter time equivalent pulse are sent to the fixed shutter time equivalent pulse counter 16, respectively. As a result, the light response pulse counter 12 stores a number corresponding to the field light, and the fixed shutter time equivalent pulse counter 16vC. The number corresponding to 1/60 second is stored, and the storage is completed when the respective timers 3 and 8 stop operating and generate a signal "0".

Now, in this case, as mentioned above, the field light is in the appropriate brightness range, so the storage in the photoresponse pulse counter 12 is performed at any stage from the first stage 121 to the third stage 123. The stored values in the rows 124 to 6 126 are "0".

Therefore, this signal "0" is narrowed down via the OR circuit 18,
Drive circuit 19 and first and second switching gate circuits 21, 2
2. Therefore, the gate of the second switching gate circuit 22 consisting of an AND circuit is closed, and only the gate of the first switching gate circuit 21 consisting of an inhibit circuit is opened.
The switching gate circuit 21 becomes ready to pass the first shutter close signal.

On the other hand, since the input signal to the aperture drive circuit 19 is "O", no aperture drive action is performed.

Therefore, the diaphragm 20 remains in its initially set position. When the normally open switch 10 is closed in order to open and close the shutter in such a state, the shutter is opened in synchronization with this and a reference pulse is sequentially sent to the reference pulse counter 13.

When the count of the reference pulse counter 13 advances and becomes equal to the value stored in the photoresponse pulse counter 12, the first shutter close signal is output from the first coincidence circuit 14 at that moment. This first shutter closing signal passes through the first switching gate circuit 21 whose gate is opened in advance as described above, passes through the OR circuit 25, and then switches to the shutter closing circuit 2.
6. This turns on the thyristor 28, energizes the electromagnet 27, and closes the shutter. The shutter is closed as described above, but if the gate of the second switching gate circuit 22 is not closed at this time, the contents of the photoresponse pulse counter 12 and the reference pulse counter 13 will become equal. After the shutter is closed, the contents of the fixed shutter time equivalent pulse counter 16 of the fixed shutter time restoration device 15 and the reference pulse counter 13 become equal, and the second matching circuit 17 outputs the second shutter closing signal. Out auto strobe circuit 2
3 is activated, causing the auto strobe tube 24 to emit light. To prevent this, the second switching gate circuit 22
is used. Next, a case where the field light is in a low brightness area will be explained.

In this case, storage is performed in the low luminance stages from the fourth stage 124 to the sixth stage 126 of the photoresponse pulse counter 12, as described above. The substitute luminance signal output from this low luminance stage is
1'', the gate of the second switching gate circuit 22 opens and the gate of the first switching gate circuit 21 closes. On the other hand, the diaphragm drive circuit 19 is driven by the low luminance signal [1], and rotates the diaphragm 20 to a predetermined value. The reason why the aperture 20 is driven to a predetermined aperture value in this manner will be explained below.

Normally, with an auto strobe, once the aperture 20 is fixed at a certain aperture value, the amount of light emitted is controlled according to the distance, so that the negative is always exposed to the appropriate amount. This predetermined aperture value is specified by each manufacturer, and is usually around F4 to F5.6. When the aperture 20 is set wide open, it is possible to control light emission to a distant place with the same guide number, but since the depth of field becomes shallow, there is a risk that the subject will be out of focus when shooting wide open. On the contrary,
In order to avoid out-of-focus, it is best to close down the aperture 20 deeply, but stopping down causes a loss of light, so F4 to F5.
(6) It becomes impossible to control light emission in a far away place compared to the case. For this reason, if a predetermined aperture value is determined in advance, ideal strobe photography can be performed. For example, F
If 5.6 is preferable, the initially set aperture should be set to Fl.
If it is set to 4 or Fll, it will automatically turn to F for flash photography.
All you have to do is switch to 5.6. When the aperture value reaches the predetermined value as described above, the normally open switch 10 is closed, the shutter opens as described above, and a reference pulse is sent to the reference pulse counter 13.

The shutter is closed when the count value of the reference pulse counter 13 and the stored value of the fixed shutter time equivalent pulse counter 16 become equal, as is the case in the appropriate brightness range. At the moment when the shutter is closed, the second shutter closing signal at this time is applied to the auto-strobe circuit 23, and the auto-strobe tube 24 emits light. Since the shutter time at this time is 1/60 second, in order to restore such a shutter time, the constant stored value of the fixed shutter time equivalent pulse counter 16 is set in advance to the reference pulse generator 7 and the fixed shutter time setting. It is selected based on the correlation with timer 8.

The reason why I chose 1/60 second is because ifC cameras, such as single-lens reflex cameras, whose shutter time is generally formed by the start of the front and rear curtains, the shutter opens fully from exactly 1/60 second. be. It is generally said that 1/60 second is the limit for camera shake, and there is also a risk of camera shake at slower speeds of 1/30 second.
Seconds are selected. Now that it has been understood that auto strobe light is automatically emitted when the sub-luminance range is reached, the structure and operation of the diaphragm drive circuit 19 will now be explained with reference to FIG.

In FIG. 2, reference numeral 30 denotes a variable resistor, which includes a fixed sliding resistor 30A and a slider 30B that slides in contact with the fixed sliding resistor 30A, and the slider 30B is linked to the movement of the diaphragm 20. It is designed to be driven.

31 is an aperture 5 drive motor that drives the aperture 20; 32 is a differential amplifier made up of transistors 32A and 32B and resistors 32C and 32E; and 33A and 33B are variable resistors and fixed resistors that constitute the voltage dividing circuit 33. be.

The differential amplifier 32 receives one input voltage V from the slider 30B.
1 is given, and the other input voltage 2 is given from the voltage dividing point of the voltage dividing circuit 33. 34 is an amplifier that amplifies the unbalanced signal from the differential amplifier 32 and supplies it to the motor 31vc via electric lines 35A and 35B, and 36 and 37 are light emitting visual objects such as lamps and light emitting diodes connected between electric lines 35A and 35B. It is.

38 is a relay switch 38 connected to the electric circuit 35A.
The relay 39 is a transistor that is turned on by the low brightness signal "1" from the OR circuit 18 and excites the relay magnet 38B. The loop opening/closing means 43 is composed of these components.

This loop opening/closing means 43 is for opening/closing a closed loop consisting of the aperture drive motor 31, the aperture 20, the variable resistor 30, the differential amplifier 32, the voltage dividing circuit 33, and the amplifier 34 using a signal from the OR circuit 18. . Next, aperture 1 like this
The operation of the drive circuit 19 will be explained.

If you arbitrarily select aperture 20 before shooting, the aperture 2
Assume that the slider 30B added to the fixed sliding resistor 30A is in the position shown in the figure. Then, whether the divided voltage 1 obtained from this slider 30B or the transistor 32 of the differential amplifier 32
It is input to A. A divided voltage V2 is inputted from the voltage dividing circuit 33 to the other transistor 32B. Under the above circumstances, the substitute luminance signal "1" from the photoresponse pulse counter 12 in FIG.
When input to
turns on.

Therefore, if the slider 30B is in the illustrated position and 1>2 (this state is assumed to be a case of a high F value, tentative VC
Since the output of the differential amplifier 32 is input to the amplifier 34 as an unbalanced signal, the motor 31 starts rotating by the amplified unbalanced signal. This rotation drives the diaphragm 20 in the direction of opening (in the drawing, the force direction of the ground line), so V1 gradually decreases, and when it reaches 1-2, the unbalanced signal becomes zero and the motor 31 rotates. is stopped, and the aperture value settles to a predetermined value.

This aperture value is about F4 to F5.6 as mentioned above. On the other hand, if the initially set aperture value is on the open side (if it is on the F2 position), contrary to the above, then the slider 3
Since 0B is on the ground line side from the beginning, it is in the state of V1 and V2. Therefore, in this case as well, the motor 31 is rotated because the unbalanced signal is inputted to the amplifier 34vC, but since this unbalanced signal is reversed from before, the rotation of the motor 31 is also reversed. Therefore, since the diaphragm 20 also rotates in the opposite direction to that described above, the slider 30B is slid toward the hot line (+E side), and when V1=V2 is reached, the rotation of the motor 31 is stopped in the same way as described above. It turns out. Therefore, in the case of the aperture 1 drive circuit 19vC shown in Fig. 2, even if the photographer sets an arbitrary aperture value that he/she desires before taking a picture, in the low luminance region, even if the F value is high, it will be low. Since the lens can always reach the specified aperture value,
Extremely advantageous strobe photography can be performed.

The reason why the light-emitting visual recognition body 36 is connected to the output end of the amplifier 34 is to display to the photographer that the initially set aperture value has been canceled and a predetermined aperture value has been obtained.

In this case, the light-emitting visual recognition body 36 is lit by the unbalanced signal, and this lighting continues while the diaphragm 20 is rotating, and is turned off when the aperture reaches a predetermined aperture value. All you have to do is close the switch 10.

If there is no such visual recognition device, it will not be possible to know when the switch 10 should be closed, so if the switch 10 is closed by mistake while the aperture 20 is rotating, strobe light will be emitted immediately. It is clear from the above-mentioned significance regarding the predetermined aperture value that the image is photographed.

Of course, even if there is no visible object, it does not necessarily mean that photography is impossible. This is because the switch 10 can be closed after the time required to reach the predetermined aperture value has been estimated in advance. Furthermore, if the light emitting visual recognition body 37 is connected to the input end of the motor 31, the following advantages will arise.

This is because it is possible to determine whether the luminance range is appropriate or inappropriate by turning on or turning off the light-emitting visual body 37. In other words,
This is because the light-emitting visual recognition body 37 in this case is turned on only when the brightness is in the substitute brightness range when the relay switch 38A is closed, and remains off when the brightness is in the proper brightness range. Therefore, if the light-emitting visual object 37 does not light up after completing the memorization in the photoresponse pulse counter 12, the photographer can immediately close the switch 10 and start opening/closing the shutter, and of course, the photographer can do so after raising the mirror. When the light-emitting visual recognition body 37 lights up, it is sufficient to wait for it to go out and close the switch 10. Further, the variable resistor 33A is used when it is necessary to change a predetermined aperture value. If strobe photography is not desirable even in the substitute brightness range due to the condition of the subject or the intention of drawing, it will be a problem if the auto strobe circuit 23 is activated. Therefore, if it is possible to take pictures based only on the subject brightness even in such a low brightness range, the appropriate brightness range may be further extended. However, in such a case, holding the camera by hand is not preferable due to camera shake, so a support stand such as a tripod is required. However, even if you shoot with a tripod in this way, if it is too dark, you will still need to shoot with a strobe, so we have proposed an appropriate brightness range variable system that takes this situation into consideration, as shown in Figure 3. explain. That is, in the electric shutter shown in FIG. 3, the optical response pulse counter 1 of the electric shutter shown in FIG.
The present invention is characterized in that appropriate brightness range variable switches 40 to 42 are provided on the line connecting the low brightness stage of No. 2 and the OR circuit 18. The appropriate brightness range variable switches 40 to 42 are switched depending on the subject and surrounding conditions or the drawing intention.

In the illustrated case, the switch 40 is turned off, so the appropriate brightness range is expanded by one step. Therefore, since photography is performed using only natural light without using strobe light, the number of shots taken using natural light increases. This is very important; for example, when shooting hand-held, the limit for beginners' camera shake safety shutter time is said to be around 1/60 seconds, while for professionals the limit is around 1/30 to 1/15 seconds. has been done.

This also depends on the situation of the subject, for example, when the brightness distribution is fine and rough, the camera shake is more likely to occur in the former case or the latter, and it is said that the quality of the photograph is degraded or less. (Of course it is possible to compare the same amount of camera shake). Examples of such subjects are the former, such as group shots of birds gathering together, or rustling tree leaves, and the latter, such as close-ups of people and faces. However,
In any case, the range is about 1/60 to 1/15 seconds, so if a professional person considers 1/60 seconds to be the limit for camera shake, then 1/30 seconds and 1/15 seconds are the limits for camera shake. This is an extremely wasteful story, as it has to be spent on

However, if the shutter time is set to 1/15 seconds in advance, beginners will always be faced with camera shake failures. Therefore, when using such switching to change the appropriate brightness range, the same camera can be used by a very wide range of photographers, regardless of whether they are beginners or professionals.

FIG. 4 shows an example of the optical response timer 3.

In the figure, 43 is a time constant capacitor, 44 is a switching transistor, and 45 is a resistor. In such a photoresponse timer 3, for example, when a power switch (not shown) is closed in conjunction with the winding of a film, charging of the time constant capacitor 43 via the photoelectric element 2 is started. During this charging time, a gate signal "1" is output from the collector of the switching transistor 44 and applied to the AND circuit 5 in FIG. Next, when the terminal voltage of the time-limiting capacitor 43 reaches a predetermined level voltage, the switching transistor 4
Since signal 4 is turned on, signal [0] is now output.

Then, the output period of the gate signal "The moon changes in accordance with the field light, and the brighter it is, the shorter this period becomes. FIG. 5 shows an example of the reference pulse generators 4 and 7. 47 is a variable resistor, 47 is a time constant capacitor, 48 is a unidirectional transistor, and 49 and 50 are resistors.

The oscillation frequency is changed by changing the variable resistor 46. As described above, the embodiments shown in FIGS. 4 and 5 are all well-known, and the present invention is not limited thereto.

Furthermore, the auto strobe circuit 23 described in the embodiment of FIG.
The camera does not necessarily need to be built into the camera, but may be configured separately so that it can be attached prior to photographing.

Further, the electric shutter of the present invention is not limited to the embodiment shown in the drawings, and it goes without saying that the electric shutter of the present invention may have the following configuration, for example.

The shutter time restoring devices 11 and 15 are not limited to the matching type shown, but may also be of the well-known addition/subtraction type, inversion type, or the like. The loop opening/closing means 43 is not limited to the illustrated position, but may be provided at any position of the open loop described above.

In this case, between the motor 31 and the diaphragm 20, or between the diaphragm 20
When the loop opening/closing means 43 is provided between the variable resistor 30 and the variable resistor 30, the loop opening/closing means 43 becomes a mechanical opening/closing means. The fixed shutter time recovery device 15 may be independently provided with a reference pulse counter.

As described above, the digital electric shutter that automatically emits strobe light according to the present invention can automatically shift to strobe photography when the brightness range where camera shake occurs is reached.

Therefore, you can get the following advantages. A. When using strobe light, the troublesome manual settings of the camera that were previously required are no longer required, which saves time and effort.

B. Even people who are not used to using cameras can easily take flash photography.

C. You can expand your skills.

D. There is no need to judge whether or not to switch to strobe photography. Furthermore, since the present invention has a structure in which the fixed shutter time is restored by a fixed shutter time restoration device made of an electric circuit, both the shutter closing signal and the photoresponsive shutter time restoration device made of an electric circuit can be obtained as an electric signal. Therefore, selection control to be applied to the shutter closing circuit and the auto-strobe circuit can be easily carried out.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the electric shutter according to the present invention, Fig. 2 is a circuit diagram showing a specific example of the aperture 1 drive circuit used in Fig. 1, and Fig. 3 is a circuit diagram showing an example of the aperture 1 drive circuit used in Fig. 1. FIGS. 4 and 5 are circuit diagrams showing other embodiments of the electric shutter. FIGS. 4 and 5 are circuit diagrams showing specific examples of the optical response timer and reference pulse generator used in the embodiments of FIGS. be. 1...Photoresponsive pulse generator, 6...Fixed shutter time equivalent pulse generator, 7...Reference pulse generator, 10...Normally open Switch, 11
......Photoresponsive shutter time restoration device, 12...
... Optical response pulse counter, 15 ... Fixed shutter time restoration device, 16 ... Fixed shutter time equivalent pulse counter, 19 ... Aperture drive circuit, 20 ... ...Aperture, 21, 22...Switching gate circuit, 23...Auto strobe circuit, 2
6... Shutter closing circuit, 30... Variable resistor, 30B... Slider, 31...
Aperture drive motor, 32...Differential amplifier, 33.
...Voltage divider circuit, 34...Amplifier, 43.
...Loop opening/closing means.

Claims (1)

[Claims] 1. A photoresponse pulse generator that outputs a number of photoresponse pulses corresponding to the intensity of field light as a gate output of a gate circuit while a gate signal is applied, and a predetermined shutter time. a pulse generator corresponding to a fixed shutter time that outputs a number of pulses corresponding to , and a light that is divided into a proper brightness stage and a low brightness stage and outputs a low brightness signal when a signal is stored in the low brightness stage. A response pulse counter is provided, and a number of light response pulses corresponding to the field light given from the light response pulse generator is stored in the light response pulse counter, and the number of reference pulses applied by the shutter release is equal to the number of the light response pulses. It includes a photoresponsive shutter time restoration device that completes the restoration of the photoresponsive shutter time and outputs a first shutter closing signal when it reaches a certain relationship with the stored value of the counter, and a multi-stage fixed shutter time equivalent pulse counter. The fixed shutter time equivalent pulses given from the fixed shutter time equivalent pulse generator are stored in the shutter time equivalent pulse counter, and the number of reference pulses applied by the shutter release is the stored value of the fixed shutter time equivalent pulse counter. a fixed shutter time restoration device that completes restoration of the fixed shutter time and outputs a second shutter closing signal when a certain relationship is established; and when a low brightness signal is output from the low brightness stage of the photoresponse pulse counter. an aperture drive circuit that sets an aperture to a predetermined value; and an aperture drive circuit that receives the low brightness signal and the first shutter close signal and outputs the first shutter close signal when the low brightness signal is absent. a first switching gate circuit; a second switching gate circuit that receives the low brightness signal and the second shutter close signal as input and outputs the second shutter close signal when the low brightness signal is present; ,
an auto strobe circuit that performs strobe light emission using the second shutter closing signal as a trigger signal when the second shutter closing signal is applied from the second switching gate circuit; Alternatively, a digital electric shutter that automatically emits strobe light, comprising a shutter closing circuit that closes the shutter when a second shutter closing signal is applied. 2 The diaphragm and drive circuit include a variable resistor that generates a variable voltage V_1 in conjunction with the movement of the diaphragm, a voltage divider circuit that generates a predetermined voltage V_2, and voltages V_1 and V_2.
a differential amplifier that receives as input an unbalanced signal and outputs an unbalanced signal until both voltages are balanced; an amplifier that amplifies the unbalanced signal; an aperture drive motor that is driven in a closing direction and stops driving when the unbalanced signal disappears; a closed loop formed by the aperture drive motor, the aperture, the variable resistor, the differential amplifier, the voltage divider circuit, and the amplifier; loop opening/closing means provided at any position and receiving the low-luminance signal as input, closing the loop when the low-luminance signal is present and opening the loop when the low-luminance signal is absent; A digital electric shutter that automatically emits strobe light according to claim 1.